Someone please help me to understand

Question

This was a 'brief' tutorial implementing callbacks in Java, i cant undersand what is going on, can anyone help. Its designed to illustrate interfaces. I know how interfaces work so you dont have to explain that. Thanks so much
public interface InterestingEvent
public void interestingEvent ();
This gives us a grip on any objects of classes that implement the interface. So, we need not concern ourselves with any other extraneous type information. This is much nicer than hacking trampoline C functions that use the data field of widgets to hold an object pointer when using C++ code with Motif.
The class that will signal the event needs to expect objects that implement the InterestingEvent interface and then invoke the interestingEvent() method as appropriate.
public class EventNotifier
private InterestingEvent ie;
private boolean somethingHappened;
public EventNotifier (InterestingEvent event)
ie = event;
somethingHappened = false;
public void doWork ()
// Check the predicate, which is set elsewhere.
if (somethingHappened)
// Signal the even by invoking the interface's method.
ie.interestingEvent ();
In that example, I used the somethingHappened predicate to track whether or not the event should be triggered. In many instances, the very fact that the method was called is enough to warrant signaling the interestingEvent().
The code that wishes to receive the event notification must implement the InterestingEvent
interface and just pass a reference to itself to the event notifier.
public class CallMe implements InterestingEvent
private EventNotifier en;
public CallMe ()
// Create the event notifier and pass ourself to it.
en = new EventNotifier (this);
// Define the actual handler for the event.
public void interestingEvent ()
// Wow! Something really interesting must have occurred!
// Do something...

Answer 1

It looks to me like EventNotifier is a class that detects some event and notifies another object that the event occurred. When an EventNotifier is created, an object that implements the InterestingEvent interface is passed and is referenced thru the ie variable. When EventNotifier detects the event, it calls the interestingEvent() method of the object implementing the interface.
This is similar to how ActionListener/ActionEvent works. It would make more sense to me to call the interface InterestingEventListener.